Touch screens allow a user to conveniently interface with an electronic display system by reducing or eliminating the need for a keyboard. For example, a user can carry out a sequence of instructions by simply touching the screen at a location identified by a pre-programmed icon. As another example, a touch screen may allow a user to transfer text or drawing to an electronic display device by directly writing or drawing onto the touch screen.
Resistive and capacitive are two common touch sensing methods employed to detect the location of a touch input. Resistive technology typically incorporates two transparent conductive films as part of an electronic circuit that detects the location of a touch. Capacitive technology, on the other hand, commonly uses a single transparent conductive film to detect the location of an applied touch. The transparent conductive film is often deposited on an insulating substrate and is covered with a thin dielectric coating to protect the conductive film from damage.
A touch location is generally determined by applying an electric field to a resistive film in the touch sensitive area. For an electrically continuous resistive film, the accuracy of detecting the location of an applied touch often depends on the linearity of the electric field in the resistive film. The electric field linearity is usually improved by forming an electrode pattern around the touch sensitive area.
A projection screen is generally a sheet-like optical device placed at an image surface of a projector or a projection system. Such a screen is capable of making visible to a viewing space an image projected by the projector onto the image surface. A projection screen can be a front projection screen in which case the image projector and the viewing space are typically on the same side of the screen. In the case of a rear projection screen, on the other hand, the image projector and the viewing space are typically on opposite sides of the screen.
Typical screen characteristics used to describe a screen's performance include viewing angle and contrast. It is generally desirable to have a projection screen that has a high contrast and disperses or scatters light into a desired viewing space.
A light control film is generally an optically transmissive film that controls the direction of an incident light that is transmitted by the film. Light control films are generally placed near or mounted on a visual display monitor for the purpose of reducing glare, increasing contrast, or providing privacy.